Free piston engine



Dec. 6, 1960 J. J. WALDROP I 2,963,008

FREE PISTON ENGINE Filed May 23, 1958 2 Sheets-Sheet 1 INVENTOR.

Deg. 6, 1960 J. J. WALDROP FREE PISTON ENGINE 2 Sheets-Sheet 2 Filed May 23, 1958 lllll 'FREE PISTON ENGINE James J. Waldrop, 117 Jonestown Road, Asheville, N.C.

Filed May 23, 1958, Ser. No. 737,273

3 Claims. .(Cl. 123-46).

The present invention relates to engines generally and in particular to a free piston engine having a turbine.

An object of the present invention is to provide a free piston engine which is simple in structure, one economical to manufacture and assemble, and one which is highly effective in action.

Another object of the present invention is to provide a free piston engine which lends itself to economical operation, one having few moving parts, and one which may be manufactured of light weight materials.

These and other objects and advantages of the pres ent invention will be fully apparent from the following description when taken in conjunction with the annexed drawings, in which: J

Figure 1 is a view in section of the engine according to the present invention.

Figure 2 is a view taken on the line 22 of Figure 1.

Figure 3 is a view taken on the line 3-3 of Figure 1.

Referring in greater detail to the drawings, in which like numerals indicate like parts throughout the several views, the engine of the present invention is designated generally by the reference numeral and includes a free piston section 12 and a turbine 14. The free piston section 12 comprises an upstanding casing 16 having flat opposed spaced end walls 18 and 20.

A first hollow cylinder 22, having an open end 24 and a closed end 26, is positioned exteriorly of the casing 16 with the open end 24 abutting the closed end wall 18 of the casing 16 and with the closed end 26 of the cylinder 22 remote from the end wall 18. A flange 20 extends about the open end 24 of the cylinder 22 and bolts 30 extend through the flange 28 and into the casing end wall 18 and comprise means by which the openend 24 of the cylinder 22 is fixedly secured to the end Wall 18.

A second cylinder 32, having an open end '34 and a closed end 36, is positioned with the open end 34 abutting the casing end wall 20. The closed end 36 of the cylinder 32 is remote from the casing end wall 20. A flange 38 similar to the flange 28 projects from the cylinder 32 adjacent the open end 34 and bolts 40 secure the flange 38 to the casing end wall 20.

The cylinders 22 and 32 are in axial alignment with each other.

A housing 42, having an open end 44 and a closed end 46, is circumposed about and concentric with and encloses the cylinder 22 and has its open end 44 fixedly secured to the casing end wall 18 -by means of a flange 48 which projects from the housing 42 adjacent the open end 44 and other bolts 50 which extend through holes provided in the flange 48 and aligned holes in the casing end wall 18.

A second housing 52, having an open end 54 and a closed end 56, is circumposed about and encloses the cylinder 32 and has its open end 54 fixedly secured by means of a flange 58 and bolts to the othercasingend 'wall 20.

2,963,008 Patented Dec. 6, 1960 its portions inwardly of its ends supported in packing gland assemblies 64 and 66 which are provided in the end walls 18 and 20, respectively, of the casing 16. The piston rod 62 has a portion 68 adjacent one end within the cylinder 22 and a portion 70 adjacent the other end within the cylinder 32. A piston 72 is carried on the piston rod portion 68 within the cylinder 22 and another piston 74 is carried on the piston rod portion 70 within the cylinder 32, both pistons 72 and 74 being movable in back and forth movements from the respective closed ends of the cylinders to the open ends thereof in response to reciprocatory movement of the piston rod 62.

Another or third piston 76 is circumposed about the portion of the piston rod 62 within the casing 16 and is fixedly secured thereto for movement from the position shown in Figure 1 adjacent the casing end wall 18 toward and away from the other casing end wall 20. Each of the pistons 72 and 74 are provided with piston rings '78, as shown in Figure 1 with respect to the piston 74, sealing the periphery of the piston to the adjacent cylinder. The piston 76 also is provided with sealing rings as at 80 in Figure 1 sealing the periphery of the piston 76 to the casing wall.

The casing end Wall 18 is provided with an ingress opening 82 for admitting air from the atmosphere into the interior of the casing 16 on one side of the piston 76. A check valve 84 is operable within the ingress opening 82 to permit air to enter the casing 16 on the right hand side of the piston 76, as seen in Figure 1, but prevents air within the casing from venting to atmosphere. The casing end wall 18 also has an egress opening 86 which connects the chamber 88 formed by the space between the housing 42 and the cylinder 22 in communication with the interior of the casing 16. A check valve 90 is operable in the egress opening 86 to permit the movement of air from the casing 16 into the chamber 88 upon movement of the piston 76 toward the right, as seen in Figure 1.

The casing endwall 20 is similarly provided with an ingress opening 92 and an egress opening 94, each provided with a check valve similarly permitting air to enter from the atmosphere into the casing 16 on the left side of the piston 76, as seen in Figure l, and permitting air to be pumped by the action of the piston 76 as it moves toward the left through the egress opening 94 and into the space between the cylinder 32 and the inner wall of the housing 52, such space constituting a compression chamber 96. e

Means is provided for injecting a charge of combustible fuel into each of the cylinders 22 and 32 in the space between their associated pistons and the end walls of said cylinders for mixing with the air in such cylinders to form an explosive mixture. This means consists in a pump cylinder 93 supported in each of the end walls of the cylinders 22 and 32, said pump 98 being conventional and common in diesel engines and here only illustrated as a plunger 100 movable back and forth in the pump 98. As each of the fuel injection means is the same as the other, it will be described with reference to the fuel injection means associated with the cylinder 32.

An actuating rod 106 extends through the housing end wall 56 and through the casing end wall 20 for sliding movement therein. A portion of the actuating rod 106 exteriorly of the end wall 66 bears against and is operatively engaged with the adjacent end of the rocker arm 102. The other end portion projects into the casing 16 and is provided with a head 108 against which the piston 76 strikes as the latter moves into face-to-face abutting relation with respect to the casing end wall 20 as a result of explosion of the fuel in the cylinder 22 between the head of the piston 32 and the end wall 26 of the cylinder 22. The other actuating rod 106 in the housing 42 is similarly provided with a head which is struck by the piston 76 when the latter is forced to the position adjacent the casing end wall 18 as a result of burning or explosion of the fuel in the cylinder 32. This actuation of the actuating rod 106 by the piston 76 effects the injection of the fuel into the opposite cylinder.

Partially surrounding each of the cylinders 22 and 32 is an exhaust manifold 110, as shown in Figure 3 with reference to the cylinder 22. The manifold is connected by a conduit 112 to an inlet 114 in the wall of a turbine casing 116. A rotatable rotor 118 is journaled on a shaft 120 in the turbine casing 116 and is driven in the direction indicated by the arrow by the exhaust gases which flow from the cylinders 22 and 32.

The cylinders 22 and 32 are each provided with a plurality of spaced inlet ports 122 and spaced exhaust ports 124, the latter being in communication with the interior of the respective conduits 112. The inlet ports 122 and exhaust ports 124 are covered by the skirt of the respective pistons 72 and 74 when the latter are in their positions, alternatingly, adjacent the closed ends of the cylinders in which they travel.

In operation, some suitable means is used to initiate the travel of the piston 72 from its position adjacent the cylinder end wall 26. As shown in Figure 1, this means may consist in a powder charge 126 in a cylinder 128 extending through the housing end wall 46 and into the cylinder end wall 26. A firing pin 130 may extend through the end of the cylinder 128 and being accessible to the engine operator for igniting the powder charge 126. Compressed air may be used as well to initiate the starting of the engine 10. Upon explosion of the powder charge 126 the piston 72 will move toward the open end of the cylinder 22 carrying with it the piston rod 62 and the piston 74. As the piston 76 moves in the casing 16 air from the atmosphere is entered through the ingress opening 82 and, at the same time, air is forced through the egress opening 94 into the compression chamber 96. Each of the cylinders 22 and 32 are provided with other ports 132 inwardly of their open ends and as the piston 74 moves toward the cylinder closed end 26 a portion of the air compressed in the compression chamber 96 flows through the ports 132 into the space between the piston 74 and the casing end Wall 20. Another portion of the compressed air in the chamber 96 enters the inlet ports 122 and is compressed in the cylinder 32 by the piston 74 as the latter travels toward the cylinder end wall 36.

Next, the piston 76 strikes the head 108 and effects the injection of a charge of fuel into the compressed air in the cylinder 32 where it explodes and drives the piston 74 in the opposite direction to compress the air in the cylinder 22 between the piston 72 and the cylinder end wall 26. Air is then drawn into the casing 16 through the ingress opening 92 at the same time that air is forced through the egress opening 86 into the compression chamber 88. As each piston 72 and 74 in turn uncovers its associated exhaust port a portion of the compressed air in the associated compression chamber flows through the inlet ports 122 and scavenges the combustion gases in the respective cylinders and flows through the conduit 112 to drive the turbine rotor 118 from which power may be taken for driving machinery as desired. Successive injection of fuel into the cylinders 22 and 32 will keep the engine running and the rotor 118 rotating.

What is claimed is:

1. A free piston engine comprising a casing having opposed end walls, a first hollow cylinder having one end open and the other end closed positioned exteriorly of said casing so that the open end abuts one of the end walls of said casing with the closed end remote from said one end wall, means fixedly securing the open end of said cylinder to said one end wall of said casing, a second hollow cylinder having one end open and the other end closed positioned exteriorly of said casing so that the open end abuts the other of the end walls of said casing with the closed end remote from said other end wall of said casing, means fixedly securing the open end of said second cylinder to said other end wall of said casing, said first and second cylinders being in axial alignment, a piston rod extending through said casing and supported in the end walls of said casing for reciprocatory movement and having the portion adjacent one end in said first cylinder and having the portion adjacent the other end in said second cylinder, a first piston on said one end of said piston rod and movable back and forth in said first cylinder responsive to reciprocatory movement of said piston rod, a second piston on the other end of said piston rod and movable back and forth in said second cylinder responsive to reciprocatory movement of said piston rod, 21 third piston circumposed about the portion of said piston rod within said casing and connected to said portion for movement with the piston rod, a first housing enclosing and spaced from said first cylinder and fixedly secured to said casing, the space between said housing and said first cylinder forming a first chamber for compressed air, a second housing enclosing and spaced from said second cylinder and fixedly secured to said casing, the space between said second housing and said second cylinder forming a second chamber for compressed air, each of said one and other end walls of said casing being provided with an ingress opening for the atmosphere to the interior of said casing and an egress opening from the interior of said casing to the first and second chambers respectively, and a fuel injection means supported in the closed end of each of said first and second cylinders for introducing combustible fuel into each of said first and second cylinders, said first and second cylinders being in communication with the interiors of said first and second chambers respectively.

2. A free piston engine comprising a casing having opposed end walls, a first hollow cylinder having one end open and the other end closed positioned exteriorly of said casing so that the open end abuts one of the end walls of said casing with the closed end remote from said one end wall, means fixedly securing the open end of said cylinder to said one end wall of said casing, 21 second hollow cylinder having one end open and the other end closed positioned exteriorly of said casing so that the open end abuts the other of the end walls of said casing with the closed end remote from said other end wall of said casing, means fixedly securing the open end of said second cylinder to said other end wall of said casing, said first and second cylinders being in axial alignment, a piston rod extending through said casing and supported in the end walls of said casing for reciprocatory movement and having the portion adjacent one end in said first cylinder and having the portion adjacent the other end in said second cylinder, a first piston on said one end of said piston rod and movable back and forth in said first cylinder responsive to reciprocatory movement of said piston rod, a second piston on the other end of said piston rod and movable back and forth in said second cylinder responsive to reciprocatory movement of said piston rod, a third piston circumposed about the portion of said piston rod within said casing and connected to said portion for movement with the piston rod, a first housing enclosing and spaced from said first cylinder and fixedly secured to said casing, the space between said housing and said first cylinder forming a first chamber for compressed air, a second housing enclosing and spaced from said second cylinder and fixedly secured to said casing, the space between said second housing and said second cylinder forming a second chamber for compressed air, each of said one and other end walls of said casing being provided with an ingress opening for the atmosphere to the interior of said casing and an egress opening from the interior of said casing to the first and second chambers respectively, a check valve in each of said ingress and egress openings for controlling the flow of air through said openings, and a fuel injection means supported in the closed end of each of said first and second cylinders for introducing combustible fuel into each of said first and second cylinders, said first and second cylinders being in communication with the interiors of said first and second chambers respectively.

3. A free piston engine comprising a casing having opposed end walls, a first hollow cylinder having one end open and the other end closed positioned exteriorly of said casing so that the open end abuts one of the end walls of said casing with the closed end remote from said one end wall, means fixedly securing the open end of said cylinder to said one end wall of said casing, a second hollow cylinder having one end open and the other end closed positioned exteriorly of said casing so that the open end abuts the other of the end walls of said casing with the closed end remote from said other end wall of said casing, means fixedly securing the open end of said second cylinder to said other end wall of said casing, said first and second cylinders being in axial alignment, a piston rod extending through said casing and supported in the end walls of said casing for reciprocatory movement and having the portion adjacent one end in said first cylinder and having the portion adjacent the other end in said second cylinder, a first piston on said one end of said piston rod and movable back and forth in said first cylinder responsive to reciprocatory movement of said piston rod, a second piston on the other end of said piston rod and movable back and forth in said second cylinder responsive to reciprocatory movement of said piston rod, a third piston circumposed about the portion of said piston rod within said casing and connected to said portion for movement with the piston rod, a first housing enclosing and spaced from said first cylinder and fixedly secured to said casing, the space between said housing and said first cylinder forming a first chamber for compressed air, a second housing enclosing and spaced from said second cylinder and fixedly secured to said casing, the space between said second housing and said second cylinder forming a second chamber for compressed air, each of said one and other end walls of said casing being provided with an ingress opening for the atmosphere to the interior of said housing and an egress opening from the interior of said casing to the first and second chambers respectively, and a fuel injection means supported in the closed end of each of said first and second cylinders for introducing combustible fuel into each of said first and second cylinders, said first and second cylinders being in communication with the interiors of said first and second chambers respectively, the fuel injection means in said first and second cylinders being operable in succession responsive to the reciprocatory movement of said third piston.

References Cited in the file of this patent UNITED STATES PATENTS 1,036,288 Matricardi Aug. 20, 1912 1,741,731 Nordensson Dec. 31, 1929 1,904,854 Clark et a1. Apr. 18, 1933 2,355,177 Pescara Aug. 8, 1944 2,452,193 Huber Oct. 26, 1948 2,503,152 Ekblom Apr. 4, 1950 2,526,384 Mercier Oct. 17, 1950 OTHER REFERENCES Cockerell, German application 1,012,777, printed July 25, 1957 (K1. 46F 7/01). 

